The Nonlinear Material Properties of Liver Tissue Determined From No-Slip Uniaxial Compression Experiments

2006 ◽  
Vol 129 (3) ◽  
pp. 450-456 ◽  
Author(s):  
Esra Roan ◽  
Kumar Vemaganti
Keyword(s):  
Soft Tissue ◽  
Uniaxial Compression ◽  
Material Properties ◽  
Liver Tissue ◽  
Mechanical Response ◽  
Strain Energy Function ◽  
Bovine Liver ◽  
Hyperelastic Material ◽  
Nonlinear Material ◽  
Material Parameters

The mechanical response of soft tissue is commonly characterized from unconfined uniaxial compression experiments on cylindrical samples. However, friction between the sample and the compression platens is inevitable and hard to quantify. One alternative is to adhere the sample to the platens, which leads to a known no-slip boundary condition, but the resulting nonuniform state of stress in the sample makes it difficult to determine its material parameters. This paper presents an approach to extract the nonlinear material properties of soft tissue (such as liver) directly from no-slip experiments using a set of computationally determined correction factors. We assume that liver tissue is an isotropic, incompressible hyperelastic material characterized by the exponential form of strain energy function. The proposed approach is applied to data from experiments on bovine liver tissue. Results show that the apparent material properties, i.e., those determined from no-slip experiments ignoring the no-slip conditions, can differ from the true material properties by as much as 50% for the exponential material model. The proposed correction approach allows one to determine the true material parameters directly from no-slip experiments and can be easily extended to other forms of hyperelastic material models.

Viscohyperelastic Material Modeling of Liver Tissue

2007 ◽  
Author(s):  
Kumar Vemaganti ◽  
Esra Roan
Keyword(s):  
Soft Tissue ◽  
Liver Tissue ◽  
Critical Role ◽  
Experimental Studies ◽  
Strain Energy Function ◽  
Bovine Liver ◽  
Disease Diagnosis ◽  
Strain Rates ◽  
The Continuum

Mechanical characterization of soft tissue plays a critical role in applications such as automated surgery, disease diagnosis and tissue engineering. Soft tissue is often modeled as an isotropic incompressible and hyperelastic material. However, it is well known that viscoelasticity plays an important role in determining the response of soft tissue to mechanical loads [1]. This work is concerned with the development of hyperviscoelastic models of soft tissue in general and liver tissue in particular. Experimental studies in uniaxial compression are conducted on bovine liver tissue at strain rates between 0.001 s−1 and 0.04 s−1. The response of liver tissue is modeled using the continuum mechanics framework using an exponential form of the strain energy function.

Hyperelastic Model Selection of Tissue Mimicking Phantom Undergoing Large Deformation and Finite Element Modeling for Elastic and Hyperelastic Material Properties

2011 ◽  
Vol 415-417 ◽  
pp. 2116-2120 ◽  
Author(s):  
Sara Golbad ◽  
Mohammad Haghpanahi
Keyword(s):  
Finite Element ◽  
Large Deformation ◽  
Material Properties ◽  
Soft Tissues ◽  
Nonlinear Behavior ◽  
Strain Energy Function ◽  
Strain Curve ◽  
Breast Cancer Diagnosis ◽  
Hyperelastic Material ◽  
Hyperelastic Model

Pathologies in soft tissues are associated with changes in their elastic properties. Tumor tissues are usually stiffer than the fat tissues and other normal tissues and show the nonlinear behavior in large deformations. There have been a lot of researches about elastography (linear and nonlinear) as a new detecting technique based on mechanical behavior of tissue. In order to formulate the tissue’s nonlinear behavior, a strain energy function is required. For better estimation of nonlinear tissue parameters in elasticity imaging, non linear stress-strain curve of phantom is used. This work presents hyperelastic measurement results of tissue-mimicking phantom undergoing large deformation during uniaxial compression. For phantom samples, 8 hyperelastic models have been used. The results indicate that polynomial model with N=2 is the most accurate in terms of fitting experimental data. To compare the results between elastic and hyperelastic model, a 3-D finite element numerical model developed based on two different materials of elastic and hyperelastic material properties. The comparison confirm the approach of other recent studies about necessity of hyperelastic elastography and state that hyperelastic elastography should be used to formulate a technique for breast cancer diagnosis.

A Parametric Investigation on the Neo-Hookean Material Constant

2014 ◽  
Vol 915-916 ◽  
pp. 853-857 ◽  
Author(s):  
Siti Hajar Mohd Yusop ◽  
Mohd Nor Azmi Ab Patar ◽  
Anwar P.P. Abdul Majeed ◽  
Jamaluddin Mahmud
Keyword(s):  
Constitutive Equation ◽  
Material Properties ◽  
Parametric Study ◽  
Strain Energy ◽  
Deformation Behaviour ◽  
Strain Energy Function ◽  
Material Constant ◽  
Hyperelastic Materials ◽  
Material Parameters ◽  
To Come

This paper assesses the Neo-Hookean material parameters pertaining to deformation behaviour of hyperelastic material by means of numerical analysis. A mathematical model relating stress and stretch is derived based on Neo-Hookeans strain energy function to evaluate the contribution of the material constant, C1, in the constitutive equation by varying its value. A systematic parametric study was constructed and for that purpose, a Matlab programme was developed for execution. The results show that the parameter (C1) is significant in describing material properties behaviour. The results and findings of the current study further enhances the understanding of Neo-Hookean model and hyperelastic materials behaviour. The ultimate future aim of this study is to come up with an alternative constitutive equation that may describe skin behaviour accurately. This study is novel as no similar parametric study on Neo-Hookean model has been reported before.

Mechanical Response of Ping-Pong Racket to Different Hyperelastic Surface Materials

2014 ◽  
Vol 941-944 ◽  
pp. 1566-1569
Author(s):  
Hong Wang ◽  
Gen Yan Wang
Keyword(s):  
Mechanical Response ◽  
Element Model ◽  
Friction Material ◽  
Hyperelastic Material ◽  
Critical Parameters ◽  
Surface Material ◽  
Material Parameters ◽  
Synthetic Rubber ◽  
Ping Pong ◽  
Surface Materials

Synthetic rubber serving as the surface material of the ping-pong racket has good elasticity and anti-friction. Material parameters such as the hyperelastic constitutive model of the synthetic rubber are some of the critical parameters related to the competition achievement of Ping-Pong. Especially, the certain surface material of the ping-pong racket may be beneficial to the certain way of the racketting technique. The material parameters’ change may change the elasticity, plasticity, and anti-friction of the surface which would affect the playing level of the athletes. In order to access the relation between the hyperelastic ability and the racketting strength, it is necessary to predict the mechanical response of the ping-pong racket to the different hyperelastic surface materials. A two-dimensional finite element model is developed to predict the mechanical response between the hyperelastic ability and the racketting strength due to the material parameters’ change of the synthetic rubber. The Mooney-Rivlin model is considered as the hyperelastic material model using ANSYS soft in order to simulate the ping-pong racket’s surface material precisely. The different surface material parameters must affect the surface stress or strain of the racket which may change the athletes’ achievement. The special batting technique may acquire the special hyperelastic materials parameters. The rule will be obtained between the hyperelastic material parameters and the stress distribution of the racket surface materials. The ability accurately predicting the mechanical response of the ping-pong racket surface will greatly help the ping-pong racket designers in determining the suitable racket to the particular technology’s athletes.

Biaxial Mechanical Response of Bioprosthetic Heart Valve Biomaterials to High In-plane Shear

2003 ◽  
Vol 125 (3) ◽  
pp. 372-380 ◽  
Author(s):  
Wei Sun ◽  
Michael S. Sacks ◽  
Tiffany L. Sellaro ◽  
William S. Slaughter ◽  
Michael J. Scott
Keyword(s):  
Soft Tissue ◽  
Strain Energy ◽  
Mechanical Response ◽  
Strain Energy Function ◽  
Elastic Response ◽  
Model Parameters ◽  
Shear Stresses ◽  
High Shear ◽  
Plane Shear ◽  
Fung Model

Utilization of novel biologically-derived biomaterials in bioprosthetic heart valves (BHV) requires robust constitutive models to predict the mechanical behavior under generalized loading states. Thus, it is necessary to perform rigorous experimentation involving all functional deformations to obtain both the form and material constants of a strain-energy density function. In this study, we generated a comprehensive experimental biaxial mechanical dataset that included high in-plane shear stresses using glutaraldehyde treated bovine pericardium (GLBP) as the representative BHV biomaterial. Compared to our previous study (Sacks, JBME, v.121, pp. 551–555, 1999), GLBP demonstrated a substantially different response under high shear strains. This finding was underscored by the inability of the standard Fung model, applied successfully in our previous GLBP study, to fit the high-shear data. To develop an appropriate constitutive model, we utilized an interpolation technique for the pseudo-elastic response to guide modification of the final model form. An eight parameter modified Fung model utilizing additional quartic terms was developed, which fitted the complete dataset well. Model parameters were also constrained to satisfy physical plausibility of the strain energy function. The results of this study underscore the limited predictive ability of current soft tissue models, and the need to collect experimental data for soft tissue simulations over the complete functional range.

scholarly journals Extracting viscoelastic material parameters using an atomic force microscope and static force spectroscopy

2020 ◽  
Vol 11 ◽  
pp. 922-937 ◽  
Author(s):  
Cameron H Parvini ◽  
M A S R Saadi ◽  
Santiago D Solares
Keyword(s):  
Material Properties ◽  
Mechanical Response ◽  
Loss Modulus ◽  
Force Spectroscopy ◽  
Model Parameters ◽  
Viscoelastic Response ◽  
Static Force ◽  
Critical Material ◽  
Material Parameters ◽  
Atomic Force

Atomic force microscopy (AFM) techniques have provided and continue to provide increasingly important insights into surface morphology, mechanics, and other critical material characteristics at the nanoscale. One attractive implementation involves extracting meaningful material properties, which demands physically accurate models specifically designed for AFM experimentation and simulation. The AFM community has pursued the precise quantification and extraction of rate-dependent material properties, in particular, for a significant period of time, attempting to describe the standard viscoelastic response of materials. AFM static force spectroscopy (SFS) is one approach commonly used in pursuit of this goal. It is capable of acquiring rich temporal insight into the behavior of a sample. During AFM-SFS experiments the cantilever base approaches samples with a nearly constant velocity, which is manipulated to investigate different timescales of the mechanical response. This manuscript seeks to build upon our previous work and presents an approach to extracting useful linear viscoelastic information from AFM-SFS experiments. In addition, the basis for selecting and restricting the model parameters for fitting is discussed from the perspective of applying this technique on a practical level. This work begins with a guided discussion that develops a fit function from fundamental laws, continues with conditioning a raw SFS experimental dataset, and concludes with the fit and prediction of viscoelastic response parameters such as storage modulus, loss modulus, loss angle, and compliance. These steps constitute a complete guide to leveraging AFM-SFS data to estimate key material parameters, with a series of detailed insights into both the methodology and supporting analytical choices.

scholarly journals Modeling of Viscoelastic and Nonlinear Material Properties of Liver Tissue using Fractional Calculations

2012 ◽  
Vol 7 (2) ◽  
pp. 177-187 ◽  
Author(s):  
Yo KOBAYASHI ◽  
Atsushi KATO ◽  
Hiroki WATANABE ◽  
Takeharu HOSHI ◽  
Kazuya KAWAMURA ◽  
...  
Keyword(s):  
Material Properties ◽  
Liver Tissue ◽  
Nonlinear Material

scholarly journals A novel elimination method of preloading force on the unconfined compression tests of soft tissue

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110106
Author(s):  
Jing Yang ◽  
Ming Hu ◽  
Zejie Han ◽  
Deming Zhao ◽  
Tao Qin
Keyword(s):  
Soft Tissue ◽  
Soft Tissues ◽  
Mechanical Response ◽  
Model Parameters ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Estimation Model ◽  
Elimination Method ◽  
The Real ◽  
Material Parameters

Accurate description of the mechanical properties for soft tissues can help surgeon predict the state during surgery. In unconfined compression tests (UCT) of soft tissue, a tiny force is typically applied to determine the starting position of compression. The preloading force will cause the obtained material parameters to deviate from the real parameters. In this paper, a novel elimination method was proposed to eliminate the effect of the preloading force. The effects of preloading force on mechanical response were analyzed by performing unconfined compression numerical tests. Different preloading force were applied in the simulation. The parameters obtained by traditional optimization method were defined as preloading material parameters. In the proposed method, an estimation model between the preloading material parameters and the preloading force was established to estimate real parameters. The proposed elimination method was verified by three sample diameters and material parameters. The results show that the material parameters obtained by proposed method are closer to the real parameters (estimated accuracy exceeds 97%). The proposed method can obtain more accurate constitutive model parameters, and eliminate the effect of preloading force.

scholarly journals Application of micro-computer tomography and inverse finite element analysis for characterizing the visco-hyperelastic response of bulk liver tissue using indentation

2021 ◽  
Vol 3 (5) ◽  
Author(s):  
Rajeswara R. Resapu ◽  
Roger D. Bradshaw
Keyword(s):  
Finite Element ◽  
Liver Tissue ◽  
Loading Rate ◽  
Time Dependent ◽  
Nonlinear Material ◽  
Computational Time ◽  
List Type ◽  
Prony Series ◽  
Time Dependent Behaviour ◽  
Dependent Behaviour

Abstract In-vitro mechanical indentation experimentation is performed on bulk liver tissue of lamb to characterize its nonlinear material behaviour. The material response is characterized by a visco-hyperelastic material model by the use of 2-dimensional inverse finite element (FE) analysis. The time-dependent behaviour is characterized by the viscoelastic model represented by a 4-parameter Prony series, whereas the large deformations are modelled using the hyperelastic Neo-Hookean model. The shear response described by the initial and final shear moduli and the corresponding Prony series parameters are optimized using ANSYS with the Root Mean Square (RMS) error being the objective function. Optimized material properties are validated using experimental results obtained under different loading histories. To study the efficacy of a 2D model, a three dimensional (3D) model of the specimen is developed using Micro-CT of the specimen. The initial elastic modulus of the lamb liver obtained was found to 13.5 kPa for 5% indentation depth at a loading rate of 1 mm/sec for 1-cycle. These properties are able to predict the response at 8.33% depth and a loading rate of 5 mm/sec at multiple cycles with reasonable accuracy. Article highlights The visco-hyperelastic model accurately models the large displacement as well as the time-dependent behaviour of the bulk liver tissue. Mapped meshing of the 3D FE model saves computational time and captures localized displacement in an accurate manner. The 2D axisymmetric model while predicting the force response of the bulk tissue, cannot predict the localized deformations.

scholarly journals Visco-Hyperelastic Characterization of the Equine Immature Zona Pellucida

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1223
Author(s):  
Elisa Ficarella ◽  
Mohammad Minooei ◽  
Lorenzo Santoro ◽  
Elisabetta Toma ◽  
Bartolomeo Trentadue ◽  
...  
Keyword(s):  
Zona Pellucida ◽  
Soft Matter ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Nonlinear Material ◽  
Prony Series ◽  
Critical Comparison ◽  
Highly Nonlinear ◽  
Good Agreement

This article presents a very detailed study on the mechanical characterization of a highly nonlinear material, the immature equine zona pellucida (ZP) membrane. The ZP is modeled as a visco-hyperelastic soft matter. The Arruda–Boyce constitutive equation and the two-term Prony series are identified as the most suitable models for describing the hyperelastic and viscous components, respectively, of the ZP’s mechanical response. Material properties are identified via inverse analysis based on nonlinear optimization which fits nanoindentation curves recorded at different rates. The suitability of the proposed approach is fully demonstrated by the very good agreement between AFM data and numerically reconstructed force–indentation curves. A critical comparison of mechanical behavior of two immature ZP membranes (i.e., equine and porcine ZPs) is also carried out considering the information on the structure of these materials available from electron microscopy investigations documented in the literature.

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